如何为返回值取决于输入的相同方法设置最小起订量？

Question

I'd like to test a method called multiple times during test, in a way where the tested method output depends on its input. I checked Moq's documentation and the following example seems to what I need.

// matching Func<int>, lazy evaluated
mock.Setup(foo => foo.Add(It.Is<int>(i => i % 2 == 0))).Returns(true);

The tested method looks like this:

Task<DimensionStructure> GetDimensionStructureByIdAsync(DimensionStructure dimensionStructure);

The DimensionStructure class looks like this, it is simplified as on the Id is important.

public class DimensionStructure
    {
        public long Id { get; set; }
    }

But when I put together the mock I need, example below, when it is called it returns always null .

_masterDataWebApiClientMock.Setup(m => m.GetDimensionStructureByIdAsync(
                    It.Is<DimensionStructure>(
                        structure => structure.Id == 101)
                ))
               .ReturnsAsync(addedToRoot);
_masterDataWebApiClientMock.Setup(m => m.GetDimensionStructureByIdAsync(
                    It.Is<DimensionStructure>(
                        structure => structure.Id == 201 )
                ))
               .ReturnsAsync(addedToFirstLevel);

The point os that the method gets different parameter and returns different objects. In both cases, it returns null . According to the doc, it should return what is in the ReturnAsync which is not null.

It works perfectly in another test where the Id property value of the object doesn't matter.

_masterDataWebApiClientMock.Setup(m => m.GetDimensionStructureByIdAsync(It.IsAny<DimensionStructure>()))
               .ReturnsAsync(addedDimensionStructure);

The question is, how to solve this?

Update - 02/29/2020

When I do not specify the call parameter then it is just working fine. It makes a bit tricky to test the method, but solvable.

_masterDataWebApiClientMock
               .Setup(m => m.GetDimensionStructureByIdAsync(
                    It.IsAny<DimensionStructure>()
                ))
               .ReturnsAsync(addedToRoot);

On the other hand I reported this case a special, possible bug case to Moq folks.

Answer 1

Having put together a test bench as follows I can see it returns correct values. It seems either my assumptions about IClassUnderTest are wrong or you might need to ensure addedToRoot and addedToFirstLevel are defined when you call your mocked method .

This probably doesn't answer your question per se, I'm however hoping this will either point you in the right direction or will prompt for more information.

using System;
using System.Threading.Tasks;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Moq; //I'm running Moq 4.13 

namespace UnitTestProject1
{
    public class DimensionStructure
    {
        public long Id { get; set; }
    }

    public interface ITest
    {
        Task<DimensionStructure> GetDimensionStructureByIdAsync(DimensionStructure dimensionStructure);
    }

    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod1()
        {
            var addedToRoot = new DimensionStructure { Id = 1 };
            var addedToFirstLevel = new DimensionStructure { Id = 2 };

            var _masterDataWebApiClientMock = new Mock<ITest>();
            _masterDataWebApiClientMock.Setup(m => m.GetDimensionStructureByIdAsync(
                    It.Is<DimensionStructure>(
                        structure => structure.Id == 101)
                ))
                .ReturnsAsync(addedToRoot);
            _masterDataWebApiClientMock.Setup(m => m.GetDimensionStructureByIdAsync(
                    It.Is<DimensionStructure>(
                        structure => structure.Id == 201)
                ))
                .ReturnsAsync(addedToFirstLevel);


            Assert.AreEqual(1, _masterDataWebApiClientMock.Object.GetDimensionStructureByIdAsync(new DimensionStructure { Id = 101 }).Result.Id);
            Assert.AreEqual(2, _masterDataWebApiClientMock.Object.GetDimensionStructureByIdAsync(new DimensionStructure { Id = 201 }).Result.Id);
        }
    }
}